Reply To: Fire modeling in state-and-transition models

[leonardo-frid]

Hi Megan,

 

Here are a couple of answers to your questions.

  

1. You may want to take a look at an article by William Reed (2006) entitled "A note on fire frequency concepts and definitions". In this article Reed shows mathematically that in almost all cases the fire cycle (syn. with fire rotation as you describe it) will be greater than the fire interval and recommends against the use of the fire cycle as a method to estimate fire probabilities in simulation models.
2. I can think of a couple of reasons why your model is not modeling the expected amount of fire based on its probability and area available:
   1. If you are running a spatial model and have defined a size distribution that expects large fires, your model may not be able to satisfy that distribution because of fragmentation in the burnable area. If this is the case you will see less fire than in a landscape where the burnable area has no barriers to fire spread.
   2. In a non-spatial model, if the sum of all probabilities for a cell (fire and non-fire) exceeds one, you will see a reduction in the realized probability of transitions that you see in your outputs.

 

Let me know if either of these are possible reasons for lower than expected fire amounts.  If not, perhaps you could share your library and I can have a look.

 

Regards,

Leonardo